examples/src/main/java/org/apache/spark/examples/ml/JavaImputerExample.java
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.spark.examples.ml;

// $example on$
import java.util.Arrays;
import java.util.List;

import org.apache.spark.ml.feature.Imputer;
import org.apache.spark.ml.feature.ImputerModel;
import org.apache.spark.sql.Dataset;
import org.apache.spark.sql.Row;
import org.apache.spark.sql.RowFactory;
import org.apache.spark.sql.SparkSession;
import org.apache.spark.sql.types.*;
// $example off$

import static org.apache.spark.sql.types.DataTypes.*;

/**
 * An example demonstrating Imputer.
 * Run with:
 *   bin/run-example ml.JavaImputerExample
 */
public class JavaImputerExample {
  public static void main(String[] args) {
    SparkSession spark = SparkSession
      .builder()
      .appName("JavaImputerExample")
      .getOrCreate();

    // $example on$
    List<Row> data = Arrays.asList(
      RowFactory.create(1.0, Double.NaN),
      RowFactory.create(2.0, Double.NaN),
      RowFactory.create(Double.NaN, 3.0),
      RowFactory.create(4.0, 4.0),
      RowFactory.create(5.0, 5.0)
    );
    StructType schema = new StructType(new StructField[]{
      createStructField("a", DoubleType, false),
      createStructField("b", DoubleType, false)
    });
    Dataset<Row> df = spark.createDataFrame(data, schema);

    Imputer imputer = new Imputer()
      .setInputCols(new String[]{"a", "b"})
      .setOutputCols(new String[]{"out_a", "out_b"});

    ImputerModel model = imputer.fit(df);
    model.transform(df).show();
    // $example off$

    spark.stop();
  }
}
